[This is for lower levels mainly]

When I played WoW I found that resources are one of the best casual money making schemes - for me it was herbalism.

You pick up herbs on your pvm rounds and you end up with a nice amount which people need to trainup their alchemy skillz. SO you can make a tidy amount on rarer herbs!

Second - dont over look first aid training - I found I could sell wool and cloth for a pretty good return on time to farm it and it comes as a by product of farming some Mobs also - so its a win-win.

In general I found you make more money [relatively and at low levels] selling to people who are training rather than selling your own crafted items? [If that makes sense?]